1. Field of the Invention
The present invention relates to a method for producing β-hydroxy amino acid and in particular, to a method for producing the β-hydroxy amino acid using a novel enzyme.
2. Brief Description of the Related Art
Amino acids such as β-hydroxy amino acid and amino acids having optical activity at an α-position are expected to be used as intermediates for pharmaceuticals. Examples of methods for producing optically-active α-alkyl serine derivatives which are optically-active amino acid derivatives having two different substituents at the α-position, and salts thereof, include the following methods:
1) asymmetric alkylation of an optically-active oxazolidine compound obtained from the optically-active serine derivative and pivalaldehyde (Seebach et al., Helvetica Chimica Acta, 1987, 70:1194-1216);
2) asymmetric aldol reaction of α-isocyano carboxylic acid ester and paraformaldehyde with an optically-active metal catalyst (Yoshihiko et al., Tetrahedron Letters, 1988, 29:235-238);
3) asymmetric alkylation of optically-active β-lactam compounds obtained from an optically active oxazolidine chromium carbene complex and an oxazine compound (Colson et al., Journal of Organic Chemistry, 1993, 58:5918-5924);
4) asymmetric ring-opening reaction of an optically-active aziridine compound (Wipf et al., Tetrahedron Letters, 1995, 36:3639-3642)
5) asymmetric alkylation of an optically-active pyrazinone compound obtained from an optically-active valine derivative and an optically-active alanine derivative (Najera et al., European Journal of Organic Chemistry, 2000, 2809-2820); and
6) Sharpless asymmetric dihydroxylation of a 2-methyl-2-propenoic acid derivative followed by introduction of a resulting optically-active diol compound into an optically-active azido compound for reduction (Avenoza et al., Tetrahedron Asymmetry, 2001, 12:949-957).
α-Methyl-L-serine is one of the promising substances which may be used as an intermediate of a medicament. In one of the known methods for producing α-methyl-L-serine by means of an enzymatic reaction, D-alanine and 5,10-methylenetetrahydrofolic acid are used as the materials, and 2-methyl serine hydroxymethyl transferase (EC 2.1.2.7) is used as the enzyme. However, this method utilizes an enzyme derived from a microorganism belonging to genus Pseudomonas, and requires the addition of expensive α-methyl-serine in order to produce an enzyme in a cultivation medium (Wilson et al., J. Biol. Chem 237:3171-3179). In addition, utilizing the enzyme derived from the microorganism belonging to genus Pseudomonas, α-methyl-L-serine is obtained from 4 mmol of material (D-Ala) with a yield of as low as 11%, which does not satisfy the requirements for practical use.